The objective of this project is to study the effects of experimental errors and environmental factors such as crystal packing on the average geometrics of proteins in the solid state. This work is expected to provide a comprehensive view of the environment of protein molecules in crystals. The project, which falls in the Resource Technology Improvement category of Resource-Related Research Projects, is improving the quality and utility of the Protein Data Bank (PDB) resource, by developing strategies: a) To detect, and if possible correct, identifiable errors in protein structures deposited in the PDB: b) To obtain useful estimates of precision for atomic coordinates; and c) To classify significant intra- and intermolecular non-covalent interactions in these structures and their effects on molecular geometry. Computer codes being developed under this data evaluation research project are being integrated into the programs that are used by the PDB to check each deposited structure. The PDB is the internationally recognized archival database for structures of biological macromolecules, and provides that this information is preserved and made available to the scientific public. Results from crystal structures are essential to development of a basic understanding of many biological processes on a molecular level. The PDB database is disrupted worldwide, and is used in a broad spectrum of research, including novel applications such as protein engineering and rational drug design.